<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        .box {
            width: 550px;
            height: 200px;
            margin: 50px auto;
        }

        .nav {
            width: 550px;
            height: 50px;
            background-color: black;
            display: flex;
            justify-content: space-around;
        }

        li {
            list-style: none;
        }
        section li:hover{
            text-decoration: underline;
        } 

        .lis {
            color: white;
            width: 80px;
            line-height: 50px;
        }

        .ul1 {
            width: 80px;
            height: 120px;
            margin-left: 0px;
            border: 1px solid #666;
            display: none;
            margin-top: -1px;
        }

        .ul1 li {
            padding-top: 10px;
        }

        .ul2 {
            width: 80px;
            height: 120px;
            margin-left: 140px;
            border: 1px solid #666;
            display: none;
            margin-top: -1px;
        }

        .ul2 li {
            padding-top: 10px;
        }

        .ul3 {
            width: 80px;
            height: 120px;
            margin-left: 280px;
            border: 1px solid #666;
            display: none;
            margin-top: -1px;
        }

        .ul3 li {
            padding-top: 10px;
        }
       
        .ul4 {
            width: 80px;
            height: 120px;
            margin-left: 420px;
            border: 1px solid #666;
            display: none;
            margin-top: -1px;
        }

        .ul4 li {
            padding-top: 10px;
        }
    </style>
</head>

<body>
    <div class="box">
        <div class="nav">
            <li class="lis">公司状况</li>
            <li class="lis">产品介绍</li>
            <li class="lis">联系我们</li>
            <li class="lis">人才招聘</li>
        </div>
        <section>
            <ul class="ul1">
                <li>1111</li>
                <li>1111</li>
                <li>1111</li>
                <li>1111</li>
            </ul>
            <ul class="ul2">
                <li>2222</li>
                <li>2222</li>
                <li>2222</li>
                <li>2222</li>
            </ul>
            <ul class="ul3">
                <li>3333</li>
                <li>3333</li>
                <li>3333</li>
                <li>3333</li>
            </ul>
            <ul class="ul4">
                <li>4444</li>
                <li>4444</li>
                <li>4444</li>
                <li>4444</li>
                <li></li>
            </ul>
        </section>
    </div>

    <script src="./jquery.js">

    </script>

</body>

</html>
<script>
    $('.lis').mouseover(function (index) {
        $('.lis').eq($(this).index()).css('color', 'red').siblings().css('color', 'white');
        $('ul').eq($(this).index()).css('display', 'block').siblings().css('display', 'none');
    });

    $('ul').mouseover(function (index) {
        $('ul').eq($(this).index()).css('display', 'block');
    });
    $('ul').mouseout(function (index) {
        $('.lis').eq($(this).index()).css('color', 'white');
        $('ul').eq($(this).index()).css('display', 'none');
    });

</script>